Molecular Basis of the β-Transition in Poly(arylene ether sulfones)

Abstract

The molecular basis for the β-relaxation in poly(arylene ether sulfones) has been established by deuterium NMR studies on specifically deuterated structures such as I. The primary mode of motion of the aromatic rings in these polymers is 180° phenyl ring flips. These flips occur with a broad distribution of characteristic frequencies (ca. 102–107 s-1). Added antiplasticizers decrease the magnitude of the β-relaxation and lead to a significant loss in ductile mechanical properties. Antiplasticizers also markedly reduce the rate of phenyl ring flips, thereby establishing this type of phenyl motion as a molecular-level process contributing to the β-relaxation. Other details of motion in these polymers are also addressed. © 1986, American Chemical Society. All rights reserved.